Trouble with Code 18613

I have read previous postings on this subject but can't find the definative answer.
02 Jetta w. 1.8t
Code 18613 Cooling system performance issues
Car runs fine. Engine runs at 190 w/ no problems!! Spoke with garage and they called round.. sounds like a shotgun appraoch. Thermastat, Engine cooling sensor, possibly even a change of wiring harness. HELP!!
If you have had this problem or know of a solution..please help!

Re: Trouble with Code 18613 (Jstanovic)

We replaced the fan module and the engine light stayed off for over a week, but then came back on!!!
I already replaced the cooling sensor. I am told to replace the thermastat and that they heard that there may be a problem with the"Plug for the coolant sensor" My mechanic stated that ther may be a "fix" for the plug problem, without replacing the wiring harness.
If anyone knows about this fix...PLEASE LET ME KNOW!!!

Re: Trouble with Code 18613 (Jstanovic)

Did you solve your problem?
I have the same code ('03 2.0 Beetle). I have replaced the temp sensor (3 times), thermostat, and faulty radiator fan motor. The CEL keeps coming back on after each repair. I got VAG-Com today and cleared the code, but if my past experience is any indicator, it will return.
VAG-COM readout says:
1 Fault Found:
18613 - Performance Malfunction in Cooling System
P2181 - 35-00 - -

Re: Trouble with Code 18613 (jhs914)

I have been told that the fault may be a faulty coennecter leading to the temp sensor. I have also been told that one fix is to replace the wiring harnes. Another "cheat" is to apply some type of grease that promotes conductivity between the the connecters. Ask your auto shop as I do not remember the type/name of the grease. However, a friend that is a jet mechanic know what I was talking about right away. In my case that seems to have worked for now.
The connexctor made sense in my case. The temp gauge always remained rock steady, but I would still get the Code.

Re: Trouble with Code 18613 (Jstanovic)

Thanks for the reply.
So I take it from your reply that you applied the conductive lubricant to the connector that attaches to the engine temp sensor and it seems to have solved your problem. Is that correct?

Re: Trouble with Code 18613 (Jstanovic)

Thanks. My cooling cel returned today after clearing it 2 days ago with VAG-COM. I removed the connector to the engine coolant temp sensor and lubed it with Vaseline. I checked continuity with Vaseline on the probes of my multimeter before doing this and found no current loss. I should know if it works in a couple of days.

An update on my problem. I found one of the radiator fans was not working, I replaced it thinking that would stop the CEL. Nope, it came back. I bought VAG-COM which gave code "18613- Performance Malfunction in the Cooling System, P2181-35-10---Intermittent". Cleared the code and it returned.
So now I have replaced the black coolant sensor with new green sensors from VW (3 times!), replaced the thermostat, and replaced a bad radiator fan. I also cleaned the connection (plug) that attaches to the coolant sensor. I do not have a temp gauge, but the red overheating light has never come on. The blue light goes out when it warms up.
I decide to take it to the stealership without telling them anything except I have a CEL, to see what they say. So they tell me I have a bad coolant temp sensor! I then tell them I have replaced it multiple times, with no effect on the CEL. I ask the mechanic to look for TSB's and I look over his shoulder while he is on the computer. The recommended procedure if replacing coolant sensor and thermostat don't work, is to run electrical tests on the ECM when the engine is hot and when cold. The only thing left to do then is replace the ECM.
I told the mechanic I would trade the POS before I bought a new ECM. They let me leave without charging me for the diagnosis. Guess they felt sorry for me.
The car drives OK with the CEL, which it would not do initially. It ran OK before I did the repairs, but would be down on power if you gave it a lot of throttle. It may have sensed that a fan was not working and wouldn't give it full throttle. I'm just going to let my wife drive it with the CEL and check it once a week with the VAG-COM to make sure no other codes have tripped. My VW dealer sells Mitsubishi and Chevrolet, so I may trade it back to him for a non VW (after I clear the CEL) and let him fix it before he sells it (and just hope the sales manager doesn't talk to the service manager!)
Sorry for the long rant.